Lighting systems for illuminating display objects, such as art objects, are frequently deficient, particularly for large objects like paintings. Small paintings or other display objects can be easily illuminated by strategically placed single lamps, but a problem is usually readily apparent when dealing with large, flat artwork. Typically illuminated by a single row of lamps, which may be mounted together in a housing, wall mounted over the painting, the lamps frequently illuminate the top third of the painting and leave the remainder of the painting dark and inadequately lighted. As a result, some galleries or private collectors increase the intensity of the lights, but then the painting can become over-illuminated in the spot lighted area, colors can fade and subtleties lost. Others attempt better illumination through use of sky lights in gallery rooms, but this is not always possible and lighting can still be uneven.
While it is always possible to mount multiple adjustable spot lights on the ceiling adjacent a large painting or other art object, multiple spot light mounts are not tidy appearing and wiring can be a problem. The optimum package for neat, compact and effective lighting would be a single array, or in the largest wall mounted paintings, two or more arrays, each with individual lamps targeting areas on the surface of the painting, and being capable of corresponding the intensity of the light arriving at the surface of the painting to the distance of the light source to the painting surface. This presents even illumination over the entire surface of the article and best presents the details of the painting.
Two dimensional art objects, more specifically paintings, best convey the intention of the artist when they are lighted uniformly, appropriately bright and with light with a “warmth” most suitable for that painting. “Picture Lights” sold for the purpose of lighting such art objects typically light with the brightness of the painting diminishing noticeably from the top to the bottom of the painting. Therefore, most paintings so lit do not meet the criterion of uniform illumination.
The “warmth” of the light is a description of the color spectrum present in the light, with “warm” light tending towards the red end of the spectrum and “cool” light tending toward the blue end of the spectrum. The quantitative description of this characteristic of light is called “Color Temperature” expressed in degrees Kelvin. The higher the color temperature, the cooler the light.
The ability to adjust the warmth of the light projected on a surface is well accepted in, say, stage lighting where “gel” filters are routinely placed in front of lights for the purpose of warming an otherwise “cool” light on a scene. Since this has never been applied to picture lighting, the use of filters to control the light on a painting is also one way of dealing with this need.
It has been common to control the intensity of the light on a painting with the use of dimmers. Such dimmers typically work by reducing the voltage to the light source. Unfortunately, the color temperature of incandescent lamps most commonly used in picture lighting will decrease as the source is dimmed, resulting in the light produced getting warmer as the light is dimmed. So, using the current technology, adjusting the brightness while keeping the preset, most desirable color temperature cannot be achieved.
The problem of uniformly lighting a painting is exacerbated the closer the light source is to the surface being lit. Thus, a painting lit with a typical picture light only inches above and inches out from the painting surface, will suffer greatly from lack of illumination uniformly. So, for example, a painting three feet tall, lit by such a light will be about one ninth as bright at the bottom as the top. The farther the light source is to a painting, relative to the paintings size, the less pronounced will be this effect.
Conventional picture lights often try to provide lighting uniformity by arraying a multiple number of lights along the width of the painting. Though this does not solve the reduction in lighting the height, it does ameliorate, to some extent, lighting uniformity along the width.
Many lighting manufacturers array a number of light sources in an elongated housing along the width of the painting in an effort to light the width of the painting which improves the lighting uniformity along the width. This approach is utilized by, but is not a subject of, the present invention.
Lighting manufacturers of products, predominantly for airfield lighting, have developed technology to control the distribution of light energy from a single light source that approximates a point source. This technology relies upon high power light emitting diodes. Such an application includes landing lights the brightness of which appears relatively constant as the plane nears landing and continuously subtends smaller angles. This technology could be successfully employed to solve the instant problem, but as such is currently too expensive to be commercially viable to this market. These methods rely upon the sculpturing of a single reflector assembly so as to redistribute the energy emitted by the light source in the desired pattern.